BARCELONA — The Abbott Xience everolimus drug-eluting coronary stent proved significantly more effective than the Taxus paclitaxel-eluting stent in preventing neointimal hyperplasia in the randomized SPIRIT II clinical trial, Dr. Patrick W. Serruys said at a joint meeting of the European Society of Cardiology and the World Heart Federation.
“The in-stent late loss curves are completely separate. So what was envisioned originally as a noninferiority trial is, as a matter of fact, a superiority trial,” said Dr. Serruys, professor of interventional cardiology at the Erasmus University Thoraxcenter, Rotterdam, the Netherlands.
In-stent late lumenal loss is widely accepted as a marker for restenosis, since both processes are driven by neointimal hyperplasia. The trouble for SPIRIT II is that the dominant topic of discussion at the European congress was the growing evidence that drug-eluting stents (DES) as a class may pose a greater long-term risk of stent thrombosis than do bare-metal stents cardiologists largely cast aside once DES became available.
SPIRIT II involved 300 patients with relatively simple de novo target coronary lesions. Only 13% were type C; the rest were the more straightforward lesion types A and B. Participants in the multinational trial were randomized 3:1 to the Xience or Taxus stent.
The Xience stent is investigational in the United States but recently gained European marketing approval. The cobalt-chromium stent carries everolimus, which is related to sirolimus and has essentially the same mechanism of action.
The primary end point in SPIRIT II was angiographic in-stent late loss in vessel diameter at 6 months follow-up. It was 0.11 mm in the Xience group, significantly better than the 0.36 mm in the Taxus group. This was reflected in the mean 16% residual stenosis at 6 months in the Xience group, compared with 21% with Taxus.
Everolimus stent recipients also had a mean 73% reduction in neointimal volume measured by intravascular ultrasound, compared with those who got the paclitaxel stent: 3.8 mm
One late stent thrombosis occurred at 53 days despite dual antiplatelet therapy in a Xience stent recipient, and another occurred at 60 days in a patient with a Taxus stent. The overall major adverse cardiac event rate in SPIRIT II was relatively low: 2.7% with Xience and 6.5% with the Taxus stent, a nonsignificant difference.
Dr. Serruys said in a press conference that it will take several more years to learn the Xience stent's late thrombosis risk. After all, it took 3 years of follow-up in very large registries to identify a possible problem with the current sirolimus and paclitaxel stents. The challenge for DES developers, he added, will be to find the right balance between preventing neointimal hyperplasia and generating quality endothelium.
SPIRIT II was sponsored by Abbott. Now underway are the 1,380-patient SPIRIT III trial, designed to support Food and Drug Administration approval of the Xience stent, and the 1,125-patient SPIRIT IV trial, also U.S.-based.
'What was envisioned originally as a noninferiority trial is, as a matter of fact, a superiority trial.' DR. SERRUYS